Sculptured bridge and sound post for stringed instruments

ABSTRACT

A sculptured bridge and sound-post structure which will reinforce the sound output characteristics, enhance the tone quality and increase the ready response of a stringed instrument, particularly in the violin family. The bridge has concave front and rear faces, reducing the thickness of the central web portion and making the bridge a more functional vibrating part of the sound-reproducing structure. The sculptured sound post further improves the conduction of sound vibrations between the front and back plates of the instrument sound box and the improved elements are readily adaptable to existing instruments without modification.

United States Patent [72] Inventor Kenneth W. Archibald 6219 Broadway, San Diego, Calif. 92114 [2]] Appl. No. [5,496 [22] Filed Mar. 2, I970 [45] Patented Sept. 7, I971 [54] SCULPTURED BRIDGE AND SOUND POST FOR STRINGED INSTRUMENTS 5 Claims, 5 Drawing Figs.

52 us. CI 84/309, 84/277 [51] Int. Cl Gl0d 1/02, GIOd 3/04 [50] Field of Search 84/307-309, 268,269, 274, 277; D56/l [56] References Cited UNITED STATES PATENTS 660,953 10/1900 Hammann 84/308 3,494,239 2/l970 Kasha 84/309 X FOREIGN PATENTS 67,320 1940 Czechoslovakia 84/277 678,938 1930 France 84/309 Primary Examiner-Richard B. Wilkinson Assistant ExaminerJohn F. Gonzales Attorney-Carl R. Brown ABSTRACT: A sculptured bridge and sound-post structure which will reinforce the sound output characteristics, enhance the tone quality and increase the ready response of a stringed instrument, particularly in the violin family. The bridge has concave front and rear faces, reducing the thickness of the central web portion and making the bridge a more functional vibrating part of the sound-reproducing structure. The sculptured sound post further improves the conduction of sound vibrations between the front and back plates of the instrument sound box and the improved elements are readily adaptable to existing instruments without modification.

PATENIEI] SEP 1 mm w T N E V m KENNETH W. ARCHIBALD ATTORNEY SCULPTURED BRIDGE AND SOUND POST FOR STRINGED INSTRUMENTS BACKGROUND OF THE INVENTION In a stringed instrument, such as a violin, the strings are supported on a bridge which rests on the body or sound box of the instrument. Vibrations of the strings caused by plucking or bowing are conducted to the sound box through the bridge and are amplified by the sound box. Since only a very small portion of the vibratory energy in the strings is actually reproduced audibly, the efficiency of the bridge as a conductor is important. In conventional instrument construction the bridge has two feet which rest on the top plate of the sound box. The foot on the low or base-string side of the bridge is positioned over a longitudinally extending bass bar, which is an internal reinforcement of the top plate. The other foot is positioned over a sound post which is generally perpendicular in the sound box and fits tightly between the top and backplates, the post conducting sound vibrations from the bridge to the backplate. It is well known that the configuration, positioning and fit of the sound post have a great effect on the tone of the instrument. Any improvement in the characteristics of the post will thus further enhance the total performance of the instrument.

SUMMARY OF THE INVENTION The bridge and sound post described herein are sculptured in such a manner as to improve their sound conducting and reproducing characteristics. The bridge is a wedgelike element, with the arched upper string supporting edge being thinner on the low or base-string side than on the other side. The front and rear faces of the bridge are cut to a concave configuration providing a reduced-thickness central web portion. Sufficient strength is retained at the sides to provide adequate string support, while the reduced thickness portion becomes a sound producing element, in addition to the normal conduction of vibrations through the bridge to the sound box.

The sound post is tapered along its length and is multisided, typically square, in cross section, with the sides longitudinally fluted or concave. By so relieving the sound post yet retaining adequate vibration-conducting properties, the post structure is made more effectively resonant and improves the conduction of vibrations between the top and backplates.

Together the bridge and sound post have been found to reinforce the sound-reproduction capability of an instrument, enhance the tone quality, increase the ready response and decrease the tonal decay rate. The gain in the sonority of the instrument extends the possible range of response and facilitates playing the instrument very softly, without significant loss of clarity.

The primary object of this invention, therefore, is to provide a new and improved bridge and sound post structure for a stringed instrument.

Another object of this invention is to provide a bridge which is concavely sculptured to provide a thin web portion with improved sound-reproducing characteristics.

A further object of this invention is to provide a new and improved bridge and sound post structure which is adaptable to existing stringed instruments without modification of the basic instrument structure.

Other objects and many advantages of this invention will become more apparent upon a reading of the following detailed description and an examination of the drawings in which:

BRIEF DESCRIPTION OF THE DRAWING FIG. 3 is an enlarged sectional view taken on line 3-3 of cm 7 FIG. 4 is a top plan view ofa blank from which the bridge is made.

FIG. 5 is a sectional view taken on line 5--5 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT The improved bridge and sound post structure is shown as fitted to a violin, but is adaptable to other instruments of similar type. The violin structure shown in FIGS. 1 and 2 is conventional and comprises a top plate 10 and a backplate 12, joined by a peripheral wall 14 to form a sound box, the top plate being internally reinforced by a bass bar 16.

Bridge 20 is generally conventional in outlinev and has a curved upper edge 22 with notches 24 for strings 26, and a pair of feet 28 and 30 which rest on top plate 10. The foot 28 on the bass or low-string side of the bridge rests over the bass bar 16, and the foot 30 on the high-string side rests near the sound post 32, which is described in detail hereinafter. Feet 28 and 30 are cut to fit the contour of top plate 10, so that the bridge seats securely with the rear face 34 thereof, substantially perpendicular to the top plate surface at the bridge.

The bridge is made from a basic blank 36 of maple or the like, shown in FIG. 4, the blank having a wide base portion 38 and tapering in a wedgelike configuration to a narrow upper edge 40. There is also a taper across the width of the bridge, the upper portion being thinner on the low or base-string side than on the high-string side. While the exact dimensions may vary, the basic proportions are indicated as an example. With a base thickness of T equal to the required width of the feet for stable support, the upper comer or arris 42 on the highstring side has a thickness T about one-half that of T,. The arris 44 on the low-string side has a thickness T about one half to two-thirds that of T The blank is prepared by cutting out the feet and shaping the upper edge, together with the string notches. Sculpturing consists of hollowing the faces of the bridge to reduce the thickness in the central web portion, the concavity 46 of rear face 34 and the concavity 48 of front face 50 being near equally concave as possible. The concavity begins above the feet to ensure adequate strength and stability, and ends below the upper edge of the bridge so that the string support is undisturbed. The concavity also stops short of the side edges of the bridge, in order to retain sufficient vertical compression strength for proper string support. As indicated in FIG. 3, the basic hollowing is of arcuate form with a radius of about 16 times T,, which has been found to provide a well-proportioned variation in thickness. The center of radius is on a line perpendicular to the particular face of the bridge. It should be understood, however, that the arcuate cut is only basic and that the sculpturing is completed by hand as necessary, in accordance with acoustic testing of the bridge at various stages.

It has been found that the deepest hollowing should be below the highest pitched string position, on the thickest side of the bridge, but the minimum thickness indicated at T should not be less than T In the hollowing process, the removal of material is stopped when any loss noted in transmitted sound is not offset by a corresponding gain in radiated sound. Transmitted sound is defined as the sound vibrations conducted through the bridge from the strings to the top plate. Radiated sound is defined as the sound actually radiated from the bridge, substantially perpendicular to its faces. The testing and measuring techniques involved are well known. Openings 52 and 54, as indicated in FIG. 2, are of traditional form and, if necessary, additional resonance can be obtained by further slight hollowing around the openings to leave small raised edges.

The sound post 32 is tapered along its length, the upper end being approximately three-fourths the size of the lower end in cross section. The basic cross section of the sound post is shown as square, but is not necessarily limited to that shape. Each side of the sound post has a longitudinal concave flute 56 extending almost to the edges, to leave blunt or slightly rounded edges 58 rather than sharp edges. At both ends the corners are also bevelled or rounded, as indicated at 60, to

avoid digging into the top and backplates when installing the sound post, which is very closely fitted in the sound box and usually held by friction. For optimum results the sound post should be oriented with one flute toward the neck end of the instrument and one toward the tailpiece end.

The tapered and fluted sound post has improved resonance over a wider range than the usual cylindrical post, and conducts vibratory energy efficiently between the top and backplates. Combined with the improved bridge, this increases the audible output of the sound box, which is further reinforced by the radiated output from the bridge. The improved audio response enables the instrument to be played more softly without loss of clarity, which is particularly effective in the low frequency range. In the upper frequency range the hollowing of the bridge increases the harmonic response.

The improved bridge and sound post are adaptable to existing instruments without modification of the basic instruments. Either the bridge or the sound post alone will provide a measurable improvement in performance, but the combination is preferred for best results.

Having described my invention, 1 now claim:

1. In a stringed musical instrument having a sound box with a top plate, a backplate and an enclosing peripheral wall, the improvement comprising:

a string-supporting bridge mounted on said top plate, said bridge being substantially wedgelike with a wide base portion and having a thin upper edge with notches for retaining a plurality of strings of successively increasing pitch across the bridge; the front and rear faces of said bridge being concave, making a reduced-thickness central web portion in the bridge;

and a sound post fitting tightly between said top plate and backplate under the high-pitch-string side of said bridge, said sound post having a plurality of concave longitudinal flutes.

2. The structure of claim 1, wherein said sound post is longitudinally tapered with the smaller end thereof at said top plate.

3. The structure of claim 1, wherein the concavity of said faces terminates adjacent the sides of the bridge, leaving side portions of the full thickness of the bridge.

4. The structure of claim 1, wherein said upper edge is wider on the high-pitch-string end than on the low-pitch-string end, and the maximum concavity of said concave faces is substantially below the high-pitch-string position.

5. The structure of claim 4 wherein said concave faces have substantially equal concavity, the concavity terminating adjacent the edges of the bridge. 

1. In a stringed musical instrument having a sound box with a top plate, a backplate and an enclosing peripheral wall, the improvement comprising: a string-supporting bridge mounted on said top plate, said bridge being substantially wedgelike with a wide base portion and having a thin upper edge with notches for retaining a plurality of strings of successively increasing pitch across the bridge; the front and rear faces of said bridge being concave, making a reduced-thickness central web portion in the bridge; and a sound post fitting tightly between said top plate and backplate under the high-pitch-string side of said bridge, said sound post having a plurality of concave longitudinal flutes.
 2. The structure of claim 1, wherein said sound post is longitudinally tapered with the smaller end thereof at said top plate.
 3. The structure of claim 1, wherein the concavity of said faces terminates adjacent the sides of the bridge, leaving side portions of the full thickness of the bridge.
 4. The structure of claim 1, wherein said upper edge is wider on the high-pitch-string end than on the low-pitch-string end, and the maximum concavity of said concave faces is substantially below the high-pitch-string position.
 5. The structure of claim 4 wherein said concave faces have substantially equal concavity, the concavity terminating adjacent the edges of the bridge. 